This invention relates to the construction of shoes generally, and more particularly to an athletic shoe sole construction having a rockable member that rocks as a wearer applies sidewardly directed forces through his or her foot to the shoe sole.
The sole of a shoe is subject to a variety of forces, both static and dynamic, as its wearer moves about. Static forces applied to the sole may vary from a vertical load relative to the top surface of the sole, for example when the wearer stands on a horizontal surface, to mixed vertical and horizontal loads relative to the sole, for example when the wearer stands on a sloped surface. The dynamic forces may likewise vary from a vertical load, such as when the wearer lands after a vertical jump, to mixed horizontal and vertical forces relative to the sole, such as when the wearer plants his or her foot to change direction. Finally, the static and dynamic forces may vary with the size and weight of the wearer and the wearer's activity level. A casual walker will exert relatively modest forces, while an athlete in competition or in training will exert relatively large forces to the shoe sole.
Although conventional shoe soles may comfortably support the foot and adequately bear the vertical forces of the wearer, shoe soles are ill-equipped to adequately bear the horizontal forces of the wearer. Consequently, as horizontal forces are applied to the sole, the foot tends to slip along the top surface of the sole. This slipping is considerably more pronounced when the shoes are used for athletic purposes, and affects the performance of the shoe. Such slipping also contributes to fatigue and ultimately fosters injury.
In addition to possible injury, fatigue and compromised athletic performance, lateral (i.e., side-to-side) sliding of the foot over the sole has other deleterious effects. It may reduce the comfort of the wearer and induce blisters and irritation of the forefoot. The sliding effect may also reduce shoe life. Repetitive sliding against the upper wall may cause the upper to tear from the sole. Thus, whenever a shoe is used in a manner requiring abrupt lateral changes of direction, the lateral sliding of the forefoot adversely affects the performance of the wearer and the performance of the shoe.